The present invention relates, in general, to a concept for increasing the efficiency of linear robotic packaging installations during normal operation and in the event of certain installation parts failing. In particular, the invention relates to a method by means of which articles from at least one article conveyor, which runs in a transporting direction, are transferred into set-down positions of at least one set-down-position conveyor, which runs in the transporting direction which is the same as, or counter to, the transporting direction of the article conveyor/s, in a robot processing line with robots arranged, in the case of set-down-position conveyors on either side, preferably on either side of a longitudinal center of the article conveyor/s of a certain width or, in the case of a set-down-position conveyor on one side, preferably to the side of the longitudinal center of the article conveyor/s of a certain width, wherein the robots pick the articles from the article conveyor/s and set them down in set-down positions on the set-down-position conveyors. The invention also covers an installation for implementing the method.
Products such as, for example, biscuits, sponge cakes or chocolate products, are frequently intended to be set down in ordered fashion at predetermined locations of a pack or of a feeding system of a following packaging installation. Examples are the ordered setting down of products in plastic trays, which are then usually additionally wrapped in a tubular bag and/or cardboard packaging or closed by a cover sheet, and in some cases provided with further packaging, or also the direct setting down of products in a feeding system such as, for example, a feeding chain or a feeding belt of a packaging installation. If the products are introduced into packs, then these can be fed to the installation or even produced directly on the packaging installation.
The products here may come directly from an upstream production process or a store, wherein, for reasons relating to safeguarding the product, hygiene and the production costs, packaging takes place usually directly following the production process. Frequently alternating products require packaging installations with an extremely high level of flexibility.
In particular the following two installation concepts are customary for packaging large-volume product streams:
A parallel arrangement of container conveyor/chain and product stream. Loading of the containers or of some other removal system, e.g. a chain, takes place preferably from two sides in counterflow, or in uniflow, operation. Counterflow operation is mostly advantageous here since it can achieve a relatively high installation capacity. Such an installation is known, for example, from U.S. Pat. No. 6,122,895. A corresponding installation has been combined in EP-A 1 717 150 with an installation for producing and for closing plastic trays.
Since the output of robots increases as the distances which a robot has to cover decrease, usually in each case two robots are arranged in pairs over the width of the product stream, wherein one robot clears away the products from the left-hand half of the product stream into a removal system on the left-hand side of the installation and one robot clears away the products from the right-hand half of the belt onto a removal system on the right-hand side of the product stream. The streams of filled containers are fed, for example, to two tube-packaging machines, which each provide the containers on the left-hand and right-hand sides of the installation with further packaging. The parallel arrangement allows a compact construction with a good system overview.
An alternative to this is provided by the variant in which the product stream and removal conveyor are arranged perpendicularly to one another. The robots here are arranged in cells, which set down the products in each case on a removal apparatus arranged transversely above the product stream. This arrangement likewise makes it possible to realize short pick & place distances. A significant disadvantage of this arrangement, however, is the large amount of space required, in particular in the case of installations with a high capacity and a large number of robots—installations with over 24 robots are known. In particular, each robot, in the case of this type of installation, has its own removal system. Since it is usually the case that the output of a single robot is too low to make full use of the following installation, these removal-conveyor streams have to be guided together again, which additionally increases the size of the installation. If the products are placed into containers, e.g. trays, these have to be fed separately for each robot.
The aforementioned disadvantages therefore mean that, in particular, in the case of large installations with a multiplicity of robots, the parallel arrangement of product stream and container stream (possibly removal-conveyor stream) is preferred, in particular in so-called counterflow operation. For reasons relating to output, as explained above, the robots are arranged preferably in pairs, and therefore one robot processes the left-hand half, and one robot processes the right-hand half, of the product stream.
One disadvantage of this arrangement, however, is that, during stoppage of one of the two removal systems, as often occurs briefly, for example, in the event of malfunctioning in the corresponding packaging system downstream or if, for example, a roll of packaging material has to be replaced, half the products cannot be packaged since the robots cannot reach the products on the opposite side of the product stream. Mostly, it is therefore necessary to stop the entire installation, or the products pass into the “overflow” and are thus usually lost. Stopping the installation is problematic, in particular, when the products are received directly from one production process, since the latter—e.g. sponge-cake baking—cannot easily be interrupted. This scenario, however, is usually the rule for this type of installation. This means that the products on that half of the installation where the removal system is stationary are lost.
If this is to be avoided, the installation can be supplemented by a storage system which receives the products during stoppage of the installation. Since the product stream can only be stopped in full, this means, however, that, if half the product stream cannot be packed because a removal system has been stopped, production has to be redirected as a whole into the store. The store has to be correspondingly large, which, in addition to the amount of space, investment and maintenance required, also means that a correspondingly long period of time is required until the products from the store are packaged when the installation is operating again. Since, in addition to the products from the store, it is also the case that packaging for current production has to continue, the installation, in addition, has to have a fairly large excess capacity in order to be able to work through a large store in addition to normal production.
An obvious solution to this problem would be to divide up the product stream, upstream of the packaging installation, into two “narrower” streams, which are processed by two narrower packaging installations, which manage without paired robots and each have just one removal system. This procedure, however, results in significantly larger and more cost-intensive installations.
Lower-capacity installations, in which just one removal system is present on one side of the installation, are also known. In the case of these installations, the robots, mostly, are arranged such that they can pick products from the entire width of the product stream and set them down on the removal system. If the product stream is wide, the necessary picking distances are correspondingly long.